Inductive angle indicator



Aug- 14, 1951 4 J. D. MALMQvlsT ETAL INDUCTIVE ANGLE INDICATOR Filed Aug. 2o, 1945 ATTORNEYS Patented Aug. 14, 1951 t INDUCTIVE ANGLE INDICATOR Johan David Malmqvist, Boliden, and Ivar l(rran Ragnar Thomaeus, Krlstineberg, Sweden, assignors to Bolidens Gruvaktiebolag, Stockholm, Sweden, a joint-stock company of Sweden Application August 20, 1945, Serial No. 611,613

In Sweden February 29, 1944 Section 1, Public Law 690, August 8, 1946 Patent expires February 29, 1964 l 2 Claims. (Cl. 33-205) For determining the direction of bore holes, In apparatus of recent types for determining for instance those that penetrate the rock or the inclination as used one had made use of loose layers of earth, a great number of methods an electromagnetic transmitting device, whereby have been used. In such methods the inclination radio frequency has been used. In this way viz. the angle between the longitudinal axis of 6 it has been possible to achieve, that frequency the bore hole and the horizontal plane is dein the transmitting device will be dependent on termined. One may also determine both the the inclination of the bore hole. However, these inclination and the angle between the longiapparatus will also require a great deal of space, tudinal axis of the bore hole and a certain veras the whole transmitting device must be lowered tical plane, for instance the magnetic meridian l into the bore hole.

plane. Sometimes the two last mentioned de- The present invention has for its object a terminations may be eiected by means of the method for remote reading in angle determinasame instrument including an earth inductcr, tions, by means of which method it is possible but instruments for this purpose often require to measure the inclination directly, while the a very large space. Therefore they have been angle indicator is positioned in the bore hole, serviceable only in such great ldirnensioned bore and without one being obliged to take up the holes as used in boring for oil. In bore holes of bore tube for each separate determination. The smaller diameter-mostly used for boring through necessary indicator devices may be so small that ores and non-metallic rocks of commercial imthey may be used also in a bore hole of a very portance, methods requiring considerably less small diameter. The invention is principally spacious apparatus must be used. In such cases characterized in that special angle indicathe inclination of the bore hole is usually detors-including one or more coils, the inductance termined in such a manner that a cylindrical or mutual inductance of which is dependent on bore tube being partly filled with a solution of the rotation angle between two or more vparts copper sulphate as electrolyte, is lowered into movable in relation to each otherare mounted the bore hole to the depth, at which the inclinain one or more tubes linked with each other. tion is to be measured. A gilt cylinder, the In carrying out the measurement the bore tubes axis of which coincides with the axis of the are lowered into the bore hole and the selfbore tube, is partly immersed into the elecinduction or mutual induction of the indicator trolytic bath. When measuring the inclination coils are measured by means of a special apan electric currentissent through the electrolytic paratus positioned in the Open and connected bath, whereby a layer of copper is precipitated with said indicators. Hereby a value of the on the surface of the cylinder. Then the inclinainclination 0f a bore tube 0r 0f the angle betion of the bore hole may be calculated by meastween two or more bore tubes linked with each uring the ellipse formed as the border line beother iS Obtainedtween copper and gold on the metal cylinder. Several advantages are sainedinusing variable This ellipse forms the intersectional line between induetenCeS fOl the angle indicators. The the horizontal plane (the surface of the liquid) IeCOI'ding iS quite eletllcal. Which involves a and the metal cynnder, The method may be more simple construction than in optical recordmodied in several different ways, for instance ing, fOr instance by means 0f a camera. As so that wax or paramn is melted in a, cylindrical the movable part of the indicator `device does vessel within a bore tube, whereupon the elliptic not directly tOuCh the Xed Dart. all kinds of intersectional line between the frozen 'surface frCtiOn iS avoided except that arising in the of the liquid and the cylinder is measured. bearings, and this friction may be made very By these methods, which'are intended for use 50 Small.

in bore holes of small diameter, the determina- As will appear from the subsequent description tion of the inclination angle will be rather un-v the indicators are Constructed in n Very Simple reliable and time consuming, as the bore tube' at Way.v .There is no necessity for using a special each determination must be taken up from the transmitting device that must be lowered into bore hole for measuring the inclination, 'which 65 the borehole. The only partsof the apparatus is a drawback. that have to be lowered are the indicator and Figure 1 is a diagrammatic, longitudinal, sectional, illustration of an indicator constructed ln accordance with the principles of this Vinvention.

Figure 2 is a diagrammatic, transverse, sec- 4 of an insulating material 31. 'I'he smaller coil Il is by means of two taps suspended in the larger tional illustration of the indicator of Figure 1.

Figure 3 is a diagrammatic illustration of the manner in which a device constructed in accordance with Figures 1 and 2 may be lowered into a borehole.

Figure 4 is a diagrammatic, sectional illustration of a modified form of angle indicator constructed in accordance with this invention.

Figure 5 is a diagrammatic, sectional illustration of the device of Figure 4, the view being taken at right angles to the view shown in Figure 4.

Figure 6 is a diagrammatic, sectional illustration of the device of Figure 4, the section being taken in a horizontal plane.

Indicators according to the present invention may be constructed in several ldierent ways. Figures 1 and 2 illustrate an indicator in longitudinal section and in transverse section respectively. A wire wound coil l with an iron core is provided with circular side plates, the one half 2 of which consists of ferro-magnetic material. A half-cylindrical sh'ell 3 of iron is freely movable around the shaft 4-4' and at the bottom centre provided with a weight 5, suitably in the form of a keel. kIf the cylinder shaft 4-4 is positioned in the horizontal plane, upon alterations of the inclination a greater or smaller part of the iron in the side plates will be surrounded by the half-cylinder 3. Thereby the resistance in the coll circuit is altered and the self-induction in the coil will obtain another value. By means of a cable at the tapping point 6, the coil 'I may be connected to an apparatus in the open, where the self-induction is measured, for instance by means of a self-induction bridge. The inclination is obtained from the value of the self-induction. By mounting the device in a bore tube in the manner shown in Figure 3, the shaft 4-4' of the coil will automatically assume a position in the horizontal plane by means of a jgimbal mounting of the shafts 4 4 and 8 8. In the bore tube 1 a cradle 9 is freely movable around the shaft 8 8', which coincides with the axis of the bore tube. In case the centre of gravity of the cradle 9 lies in a plane which contains the shaft 8-8' and is positioned perpendicularly to the shaft 4 4', the cradle will always set in such a manner that the shaft 4--4' lies in the horlzontal plane, and in this way one will always obtain the same self-induction in the coil I for a certain inclination of a bore hole to the horlzontal plane.

In Figures 4, 5 and 6 there is shown an angle indicator device based on the mutual self-induction between two coils. Figure 4 shows a longitudinal section of the device and Figures 5 and 6 show the same device, laterally and from above. The indicator device itself which is mounted in the bore tube 32, consists of two coils 33 and 3l, rotatable in relation to each other. The coil 33 is suspended in two taps and is rotatable around a shaft parallel to the shaft of the bore tube. One of the taps rests in a groove of thev metal casing 35, whereas the other tap rests in the groove of the metal bolt Il, which is insulated from the other part of the metal casing by means coil and is rotatable around a shaft perpendicular to the rotating shaft rst mentioned. By means of the weights 38 and 38 the larger coil will always be positioned so that the rotating shaft of the smaller coil is maintained in the horizontal plane and by means of the weight 3l the smaller coil will be maintained in the horlzontal plane, and the angle between the two rotatable coils will be the same as the angle between the shaft of the bore tube and the horizontal plane. In case the two coils are coupled in series for instance in such a way as shown in Figure 4, the self-induction in the system coupled in series will be dependent on the angle between the coils. In case the self-induction is measured at the tapping point 40, aA value of the inclination of the bore tube is obtained. If the coils are arranged parallel to each other, viz. when the bore tube is horizontal, the self-induction will be at maximum in case the two coils are Wound in the same direction. On the contrary, when the coils form an angle with each other of 90 the selfinduction will be considerably less or equal to the total of the self-inductions of the two coils.

Angle indication according to the principle o! mutual induction, viz. when using two movable coils, is, of course, also possible to use in determining the angle between two or more bore tubes.

In the above mentioned way it is also possible to measure mutual induction between two coils, one of which being freely movable, so that its position is adjusted by the magnetic meridian field (compass) or by a gyro field (gyro compass), the other one being firmly attached to the bore ube.

If a certain damping of the movement of the movable parts of the angle indicator is necessary, a suitable damping liquid may be used in all the constructions.

Angle indication according to the present invention may, of course, be used for other purposes than for measuring directions of bore holes. Generally, it may be used for the determinations of angles at a great distance from the measuring place. For instance directions under water or in subways and other hollows in the ground difcult of access may be determined in the above described manner.

Having thus described our invention we declare that what we claim is:

1. An indicator for making inclination or angular determinations within bore holes of very small diameters comprising an outer fiat coil rotatable about a shaft lying in the same plane as said coil and included in the rotatable system of the outer coil, said shaft being mounted in means adapted to be lowered into the bore hole and the direction of the shaft being the same as the direction of the bore hole, and an inner fiat coil rotatable within said outer coil and about a shaft the axis of which lies in the same plane as said coil and is perpendicular to the axis of the rotatable system of the outer coil and attached to said system, the rotational axes of said two coils lying in the same yplane whereby changes in the position of said indicator cause relative movements between the two coils with consequent measurable alterations in their mutual inductance.

2. An indicator for making inclination or angular determinations as claimed in claim 1, characterized in that the centre of gravity of the outer coil is located offset of the rotatable axis of said 5 outer coil. the arrangement being such that the rotatable axis of said outer coil always is selfaligned in a vertical plane containing the axis of the bore hole, and that the centre of gravity REFERENCES CITED The following references are of record in the file of this patent:

Num'oer 8 UNITED STATES PATENTS Name Date Schoute et al. Apr. 6, 1920 Hester July 26, 1932 Lord Oct. 25, 1932 Schlumberger Nov. 6, 1934 Smith Apr. 30, 1935 Palmer et al Aug. 20, 1935 Miller Apr. 27, 194,3

FOREIGN PATENTS Country Date Number Great Britain Dec. 13, 1939 

